Package and method and apparatus for forming same



June 16, 1964 E. c. SLOAN ETAL 7,

PACKAGE AND METHOD AND APPARATUS FOR FORMING SAME Filed Nov. 27, 1959 3Sheets-Sheet 1 A INVENTORS- Edward C 5Z0a7Z,

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Hobart L 6066/,

, @MZZM yvm June 16, 1964 E. c. SLOAN ETAL PACKAGE AND METHOD ANDAPPARATUS FOR FORMING SAME Filed NOV. 27, 1959 5 Sheets-Sheet 2 INVENTORS Edward C 5Z0cz7z, Qgaafwf! Eberrrzam barf GOZZCZI, W P

June 16, 1964 E. c. SLOAN ETAL PACKAGE AND METHOD AND APPARATUS FORFORMING SAME INVENTORS Edward C 70072 zZzg/wmflfeffizarz 3 Sheets-Sheet3 IBI I'IIIIIIII'I|.ll|||rl|| Filed Nov. 27, 1959 United States Patent3,137,580 PACKAGE AND METHOD AND APPARATUS FGR FORMING SAME Edward C.Sloan, Augustus H. Eberman, and Robert I Goller,Madison, Wis assignorsto (lscar Mayer & Company, Inc, Chicago, 121., a corporation of IllinoisFiled Nov. 27, 1959, Ser. No. 855,784 12 Ciaims. (Ci. 99l7 1) Thepresent invention relates to a new and improved package, the method offorming the package, and apparatus suitable for use in practicing themethod. More specifically, the invention is directed to the utilizationof supercooled polyvinylidene chloride films in formingproduct-containing packages in a manner to make full utilization of theadvantageous supercooled properties of the films, the packages formed inaccordance with the teachings of the present invention exhibitingimproved properties including improved flexibility capable ofwithstanding normal and even severe impact handling.

In the co-pending application Serial No. 711,916, filed January 29,1958, issued as Patent No. 3,083,106, a special package particularlyadapted for merchandising meat products, such as wieners, is disclosedthis package being formed from polyvinylidene chloride film in itssupercooled state. Such film is formed from vinylidene chloride-vinylchloride copolymers such as Saran manufactured by Dow Chemical Companyof Midland, Michigan. This type of filmis obtained as a powder, heatedto a state of plastic flow and extruded into a continuous film of anydesired thickness. This film when immediately supercooled followingextrusion (cooled to a temperature adequate to retard crystallization,such as around room temperature) exhibits unique self-sealing coherenceas well as uniform stretchability while maintained in an amorphousstate. These unique properties have been utilized to advantage inaccordance with the teachings of the aforesaid application in formingmany different types of packages with the utilization of polyvinylidenechloride films being greatest at the present time in packaging foodproducts, particularly meat products.

The self-sealing aspect of the supercooled film is adequately efficientto merely require the contacting of portions of the film and does notnecessitate the application of mechanical pressure thereto or the use ofextreme conditions such as high temperature heating or the like. Astaught in the application, the self-sealing property of supercooledpolyvinylidene chloride film has been efficiently utilized bysuperimposing portions of the film or films about a product in suitablepackage forming apparatus with hermetic sealing being accomplished bythe mere vacuumizing of the package resulting in the drawing of thesuperimposed portions of the film together for adequate self-sealingcontact therebetween. In this manner, a fused, permanent seal may beobtained which not only establishes hermetic conditions but alsomaintains the same.

As disclosed in the aforementioned co-pending application, the use oflaminates of polyvinylidene chloride film in forming food packages hasbeen considered. Preferably, such laminates include the utilization oftwo separately formed polyvinylidene chloride films each of whichexhibits certain desirable properties, the films being contacted andfused together while in their supercooled state. In this respect, atwo-ply packaging film laminate may be formed from an inner ply ofhighly flexible polyvinylidene chloride film and an outer ply of highoxygen barrier polyvinylidene chloride film, the flexibility of theinner ply being imparted to the laminate with the oxygen barrier plymaterially improving the product keeping properties of the packageformed from the laminate. Due to the self-fusing properties of thesupercooled film, the laminate in effect becomes a single film. Suchlaminates are useful in instances where the packages are not subjectedto severe impact during handling.

In connection with the use of a laminate of the type described, it hasbeen found that some limitations exist which under certain circumstancesshould advantageously be overcome. The impact strength of the laminateis no better than that of the oxygen barrier film alone and where. thepackage is subjected to rather severe handling conditions, fracture ofthe laminate may occur. Where the package formed is of an overallflexible type particularly in the seal-defining area, the handlingconditions of this package may be so severe as to cause fracture orfailure of the package particularly in the seal-defining area. Thepackage may be handled and subjected to impact forces any number oftimes subsequent to forming and prior to final merchandising and it isoften the case that packages shipped over substantial distances aresubjected to rather severe climatic changes. Under such conditions thetwo fully cohered plies of the film laminate are subject to fracture orfailure.

It is an object of the present invention to provide a new and improvedpackage formed from a laminate of polyvinylidene chloride film, thelaminate being specially prepared to improve the flexibility andstrength thereof while retaining and making full utilization of theunique supercooled properties of polyvinylidene chloride film forming apart thereof.

A further object is to provide a new and improved package utilizing inthe forming thereof a laminate of two-ply polyvinylidene chloride filmwith the plies being maintained separate throughout'by the placementtherebetween of a separating material which does not interfere with theuseful properties of the individual plies and yet still provides aunitary laminate for efficient package forming use.

Another object is to provide a new and improved package formed from one\or more laminates of inner and outer polyvinylidene chloride films,these films being maintained in non-bonded condition by a separatingmaterial received therebetween, the separating material used being ofsuch a nature as to permit full and eflicient utilization of the uniquesupercooled properties of polyvinylidene chloride film.

Still a further object of the present invention is to provide a new andimproved method of forming packages, the method providing for theforming and utilization of a laminate of supercooled polyvinylidenechloride film which includes as a part thereof a separating materialcooperating to increase the utilization of the laminate.

A further object is to provide new and improved apparatus for use incarrying out the method of the present invention.

Other objects not specifically set forth will be apparent from thefollowing detailed description of the present invention made inconjunction with the accompanying drawings wherein:

FIG. 1 is a plan view of one form of package formed in accordance withthe teachings of the present invention;

FIG. 2 is an enlarged fragmentary section of a portion of the package ofFIG. 1 taken generally along line 22 therein;

FIG. 3 is a View similar to FIG. 2 illustrating a modification of thetype of laminate used in forming the package of FIG. 1;

FIGS. 4A and 4B are partly sectioned, fragmentary and diagrammaticillustrations of a package forming apparatus suitable for use in formingthe package of the present invention;

FIG. 5 is a fragmentary top plan view of the package forming portion ofthe apparatus of FIGS. 4A and 4B;

FIG. 6 is a fragmentary, diagrammatic illustration of a modified portionof the apparatus of FIGS. 4A and 413;

FIG. 7 is a sectional elevation of the apparatus of FIG. 6 takengenerally on line 77 therein; and

FIG. 8 is a fragmentary plan view of the laminate forming portion of theapparatus of FIG. 6 taken gen erally along line 88 therein.

The polyvinylidene chloride film laminate formed and utilized in packagepreparation in accordance with the teachings of the present inventionincludes the utilization of an inner and outer supercooledpolyvinylidene chloride film, the combined films being separated atleast substantially throughout by the insertion therebetween of aseparating material such as a thin layer of oil, oily substance,oil-containing material or a flexible film which is not bondable to thesupercooled polyvinylidene chloride films to an extent that thepolyvinylidene chloride films are, in effect, fused to one another. Apackage It formed from a pair of laminates of the type described isillustrated in FIGS. l3. This package is of the general type disclosedin the aforementioned co-pending application and includes an upperlaminate 11 combined with a bottom laminate 12, these laminates takingthe shape of a plurality of elongated products 13 received therebetweenand arranged in side-by-side relation, the products 13 being wieners orother similar food products. As best illustrated in FIG. 1, the package10 is generally flexible and is formed by the placing of a number ofwieners 13 between the two laminates 11 and 12 while these laminates arein their supercooled state insofar as the polyvinylidene chloride filmsforming a part thereof are concerned. As fully described in theaforementioned co-pending application, the laminates 11 and 12 arebrought together about the products 13 by the use of a vacuum and acontinuous, radially outwardly directed, flange-like side margin seal 14is obtained. The supercooled properties of the polyvinylidene chloridefilms provide for adequate stretching of the films in response tovacuumization therebetween to result in a drawing together of the filmsabout each of the individual products 13 to fully conform to the shapeof adjacent surfaces thereof as best illustrated in FIGS. 2 and 3. Thesupercooled properties further provide for the forming of a continuoushermetic seal of fused-type throughout the flange-like seal area 14. Forease of handiing, the individual wieners 13 are preferably held togetherin side-by-side relation by a known type of paper band 15 appliedthereto prior to packaging thereof.

As illustrated in FIG. 2, the laminates 11 and 12 may each be formedfrom an inner highly flexible film 15 of polyvinylidene chloride, anouter oxygen barrier film 16 of polyvinylidene chloride and anintermediate separating film 17 of any suitable material which exhibitsadequate flexibility and which is not bondable with polyvinylidenechloride film, particularly when the latter is in its supercooled state,to an extent that the polyvinylidene chloride lms are, in effect,fixedly bonded to one another. In

addition to the foregoing properties, an important requisite of theseparating film material 17 is that it must be formable to permit fullutilization of the unique stretch properties of supercooledpolyvinylidene chloride film. As previously described, the laminates l1and 12 are stretched during vacuumization of the package to fullyconform with and take the shape of the products enclosed thereby.Accordingly, the intermediate separating film material 17 mustlbecapable of stretching to the desired extent so as not to defeat orinterfere with the important package shaping property of amorphouspolyvinylidene chloride film. Examples ofsuitable separating filmmaterial are polyvinyl chloride r1151; polyethylene film and polyvinylalcohol coating-like film. V u

The provision of a separating film 17 in each of the laminates 11 and 12materially increases the impact resistance of the laminates and theoverall strength and usefulness of the package Ill. The separate anddistinct properties of the inner and outer polyvinylidene chloride filmsof each laminate are retained intact and are not altered by completefusing of the films together while the same are in their supercooledstate. The inner polyvinylidene chloride film 15 provides to a fulldegree the flexibility desirable in the package it) and the outerpolyvinylidene chloride film 16 provides to a full degree the oxygenpermeability resistance necessary to maintain the product keepingproperties of the package 10. As a result, the

eparating film material permits the two different types ofpolyvinylidene chloride film to retain their separate properties and actindependently of one another while further permitting laminate formationand utilization.

In accordance with the preferred package forming pro cedure of thepresent invention, a series of interconnected packages 16 are formedfrom continuous sheets of the film material as will be more completelydescribed. An etficient hermetic seal along the seal area 14 is obtainedby reason of the permanent fusing of the inner plies 15 ofpolyvinylidene chloride film of the upper and bottom laminate 11 and 12.The supercooled properties of the contacting inner films 15 of thelaminates 11 and 12 provide for the forming of a very elficient hermeticseal and while the separating film 17 has been described as beingnon-bonded to the polyvinylidene chloride film, it will be understoodthat this condition is of a nature merely adequate to permit retentionof the individual properties and functions of the polyvinylidenechloride films 1S and it. In other words, there is adequate adherencebetween the films 15 and 17 and 16 and 17 of each of the laminates 11and 12 to permit forming and handling thereof for package preparationand prevent fraying thereof along the marginal portions of the seal area14 to an extent that the formed package 10 is not damaged, but theseparated polyvinylidene chloride films are not fused'together.

FIG. 3 illustrates a package 10 which is modified in connection with theseparating material utilized between the polyvinylidene chloride films15 and 16 of the laminates 11 and 12. The separating material 18 in thisinstance is an oil or an oily-like substance. By way of example, theseparating material 18 may be a thin layer of an oil-containing materialsuch as an emulsion or a mixture of oils, a straight mineral oil,silicone oil, a polyvinyl alcohol film-like coating or a suitableplasticizer. The separating material 18 may be of any suitable typewhich is capable of forming a very thin film adequate to maintainseparation between the polyvinylidene chloride films 15 and 16 of eachof the laminates 11 and 12. The

substances used prevent fusing of the films 15 and 16 while the same arein their supercooled state and provide for full and separate retentionoftheir individual properties as well as adequate flexibility retentionof each of the laminates to withstand severe impact during subsequenthandling of the finished package. Here again, an adequate hermetic sealis formed by the fusing of the inner polyvinylidene chloride films 15 ofeach of the laminates 11 and 12 and the oily separating material ispresent in such a thin film that there is no appreciable fraying orseparation of the outer polyvinylidene chloride films 16 of thelaminates 11 and 12 in the seal area 14. However, the apparatus of thepresent invention makes use of an edge sealing feature as a means ofcontrolling application of the oil between the amorphous polyvinylidenechloride films as will be described. This feature provides a specialedge seal 19 along two opposite side edges of each package. The edgeseal 19 results in the polyvinylidene chloride film plies of eachlaminate being fused together as shown in FIG. 3 but the width of theedge seal is maintained at a minimum so as not to detract from thestrength of the main seal area 14.

FIGS. 4A and 4B diagrammatically illustrate a preferred form ofapparatus used in forming the package 10 of the present invention. FIG.4A shows apparatus used in forming'laminates of the type illustrated inFIG. 2. In FIG. 4A a battery of film extruders 20 is suitably mountedover a tank 21 which holds therein a quantity of cool water 22constituting the supercooling bath. The extruder battery 20 includes aplurality of hoppers 23 which supply powdered film forming materialthereto for heating to separated plastic masses which are thenindividually extruded through film forming members or extruder means 24,25, 26, 27 and 28. The extruder means 24 and 28 each deliver acontinuous sheet of oxygen barrier polyvinylidene chloride film used informing the outer plies 16 of the laminates 11 and 12 previouslydescribed. The extruder means 25 and 27 form the separating films 17 ofthe laminates 11 and 12. The extruder means 26 is in the form of adouble slot extruder and supplies two continuous sheets of highlyflexible polyvinylidene chloride film which constitute the inner plies15 of the laminates 11 and 12.

Two separate sets of combining means in the form of paired rollers 3t)and 31 receive therebetween the individual films 15, 16 and 17 tocombine the same and form the separate laminates 11 and 12. Thecombining means are submerged in the supercooling bath 22 and thepolyvinylidene chloride films 15 and 16 are supercooled immediatelyfollowing extrusion to maintain the same in their amorphous state.

The laminates 11 and 12 are delivered through the supercooling bath 22and maintained separate therein by rollers 32 and are moved ontoseparate conveying means 33 for delivery toward a package formingmachine generally designated by the numeral 34 and having the first partthereof shown in FIG. 4A with the final part thereof shown in FIG. 4B.The laminate 12 is continuously delivered as guided by a roller 35 intosurface engagement with a series of bottom die forming plates 36 whichare suitably attached to a chain drive driven by spaced drive means inthe form of paired sprockets 37 and 38. The bottom die forming plates 36are arranged in an endless series for continuous movement throughout thelength of the package forming portion of the apparatus 34 includingreturn of the same in inverted position beneath the apparatus forcontinuous re-use. The package forming apparatus 34 illustrated in FIGS.4A, 4B and is of the type described in detail in the aforementionedco-pending application. The salient features of this apparatus will bebriefly described, it being understood that any suitable package formingapparatus may be utilized in carrying out the method of the presentinvention in forming the particular type of package disclosed.

At the forward end of the apparatus 34 where the laminate 12 contactsthe bottom plates 36, a product loading unit 40 is located to place thebanded wieners 13 on the laminate 12 over each of the individual bottomplates 36. As best illustrated in FIG. 5, to each side of the series ofbottom plates 36 are package forming die side wall defining assembliesgenerally designated by the numerals 41 and 42. These assemblies includebasically a plurality of continuously moving fork members 43 which movesubstantially transversely into and out of die forming relation with thebottom plates 36. The separate series of fork members are arranged forsynchronized movement with the continuous series of bottom plates 36 andoppositely positioned forks 43 supplied by the cooperating assemblies 41and 42 provide converging side wall portions with the bottom plates 36.The forks 43 of each assembly 41 and 42 are suitably driven to move withthe plates 36 centrally of the packaging apparatus 34, the forks 43being continuously returned along each side of the apparatus in thedirection of the arrows in FIG. 5.

The mating of the forks 43 and the bottom plates 36 with the laminate 12therebetween is gradual as best illustrated in FIG. 5 with the forks 43being moved diagonally in paired relation into superimposed positionrelative to the bottom plates 36 and on top of the bottom laminate 12.The top laminate 11 as shown in FIG. 4A is delivered from the conveyormeans 33 under a roller 44 which directs the laminate 11 down onto andagainst the top surfaces of the combined forks 43 to cover the interiorthereof including the product 13 therein thus defining an enclosedproduct receiving area between the laminates 11 and 12 and the forks 43.Following this portion of the functioning of the apparatus 34, acontinuously moving, endless series of top die plates 45 chain driven bysprockets 46 and 47 are brought into mating engagement with the combinedforks 43 and into registration with the bottom plates 36. The top plates45 provide covering plates relative to the product containing area ofthe completed dies with the laminate 11 being engaged between the topplates 45 and the top surfaces of the combined forks 43. a

The top plate assembly has associated therewith as schematically shownin FIG. 4A a known type of rotary valve assembly 48 which is connectedby separate series of flexible tubes or hoses 50 to each of the topplates 45. The'operation of the valve 48 is synchronized with themovement of the top plates 45 and the assembled dies are evacuated,swept with an inert gas, and further evacuated with automatic packageformation resulting by use of the rotary valve assembly 48 which hasassociated therewith conventional vacuum impressing means, an' inert gassupply or any other suitable means capable of supplying gas or vacuumfor package forming purposes. The impressing of the vacuum within theproduct containing area of the closed dies results in a drawing togetherof the areas of the laminates 11 and 12 contained therein to form theindividual packages 10 of the type previously described. The initialseparation of the laminates during evacuation and sweeping of thepackage forming cavities is accomplished in the manner disclosed in theaforementioned application and does not constitute a part of the presentinvention.

Following the package forming operation as illustrated in FIG. 4B, thetop plates 45 move out of association with the forks 43 and bottomplates 36. The bottom plates 36 at the same time move out of associationwith the paired forks 34 thus leaving these paired forks supporting theseries of interconnected packages 10. At this stage of the packageforming operation the continuous laminates 11 and 12 are unbroken butare subdivided into longitudinally spaced interconnected packages. Thesupercooled properties of the polyvinylidene chloride films of thelaminates 11 and 12 still exist and have been efiiciently utilized informing the individual packages 10. It is now preferred to advancecrystallization of the polyvinylidene chloride films adequately todestroy or overcome the supercooled properties thereof and remove anyself-coherence tendencies. Crystallization can be furthered by heatalone without it being necessary to stretch the films and heat ispreferably used without attendant stretching to prevent distortion ofthe packages formed. By reason of crystallization occurring withoutmaterial stretching of the films, the crystals are formed at randomwithout material orinetation throughout the polyvinylidene chloridefilms.

As illustrated in FIGS. 4B and 5, the supported packages move under aheating element 51 which may be of any desired length to heat thepackage films to the requisite crystallization temperature. A packageholding and separation assembly located beyond the heating element 51 isutilized to separate the individual packages 10 from the continuouscombined laminates 11 and 12. This assembly includes the use of aplurality of top die elements 52 which are carried by a suitablecontinuously moving endless belt or chain assembly driven by rollers orpaired sprockets 53 and 54. The top die elements 52 move into and out ofpackage separation relationship with the paired forks 43 and includesuitable cutting blades which pierce the combined laminates about eachpackage and cut the same to remove the package without destroying themarginal continuity of the combined laminates. In bringing this about,the top die elements 52 have cooperating therewith a synchronized seriesof bottom die elements 55 which are similarly driven by sprockets 56 and57. V The combined die elements 52 and 55 are received within the pairedforks 43 in surrounding relation with the individual packages 10 thereinlected on a spool 60 (FIG. 4B) and the separated forks 43 are returnedto the front of the package forming apparatus. The packages 19 areformed in a continuous eificient manner by the package forming apparatus34 described with full utilization being made of the unique propertiesof supercooled polyvinylidene chloride film.

FIGS. 6-8 illustrate the manner in which the laminates 11 and 12 of thepackage 10 of FIG. 3 are formed with the oily separating material 13being utilized. In utilizing the separating material 18, the film supplyand laminating portion of the apparatus previously described ismodified. FIG. 6 illustrates the utilization of an extruder assembly 63provided with a plurality of hoppers 64 by which powdered film formingmaterial is delivered into individual extruder means 65, 66 and 67. Theextruder means 65 and 67 supply continuous sheets of oxygen barrierpolyvinylidene chloride film 16 andthe extruder means 66 supplies twoseparate continuous sheets of highly flexible polyvinylidene chloridefilm 15. Immediately below the extruder means, separate sets of pairedrollers 68 and 69 are positioned to engage marginal edge portions of theextruded films to pair up the spearate films and 16 to form thelaminates 11 and 12. As particularly shown in FIGS. 7 and 8, the sets ofpaired rollers 68 and 69 are positioned along opposite edge margins tocombine the two sets of films 15 and 16 and fuse the marginal edgesthereof together without fusing the films between their marginal edgesin connection with ultimate formation of the edge seal 19 referred toabove in conjunction with FIG. 3. Each of the rollers 68 and 69 aremounted on the ends of rotatable shafts 70 which are suitably driven bymeans not shown.

The films 15 and 16 as initially formed are in an.

amorphous state with temperatures being relatively high and approachingextrusion temperatures. Accordingly, the combining of the edge portionsof these films by the sets of paired rollers 68 and 69 results in thefusing of these edge portions and the defining of pockets intermediatethe edge portions. To maintain these pockets and prevent self-sealingcoherence between the combined films 15 and 16 between their fused edgeportions, a quantity of oily separating material 18 is maintainedimmediately below each of the sets of rollers 68 and 69. The edgeportions-of the films 15 and 16 are sealed above the top surface of theoily separating material 18 and in this manner the material is retainedbetween the films intermediate their edge margins.

The edge sealed films are immediately delivered downwardly into asupercooling water bath 71 contained in a suitable tank 72 wherein thetemperatures of the films are immediately reduced to about roomtemperature or below adequate to supercool the films and maintain thesame in an amorphous state. Within the supercooling bath 71 separatesets of paired film combining rollers 73 and 74 are suitably mounted toreceive therebetween the combined films 15 and 16 and the oilyseparating material 18 trapped therebetween. As illustrated in FIG. 7,the combining rollers 73 and '74 are suitably mounted on rotating shafts75 each havingan end received in a journal 76 mounted in the tank 72with the remaining driven end extending through the tank wall andsupported by a suitable journal 77 and extending therefrom intoengagement with a suitable drive means not shown. The combining rollers73 and 74 define the bottom of the pocket in which the oily separatingmaterial 18 is retained. As the films 15 and 16 pass between the pair ofrollers 73 and 74, the separating material 18' is forced from betweenthe films to an extent to leave only a very thin film of separatingmaterial therebetween. In this manner the pockets of oil are maintainedas illustrated in FIG. 6 7

audit is necessary merely to replenish the oil supply in these pocketsfrom thee to time. a

The laminates 11 and 12. are thus formed and move through thesupercooling bath 71 as guided by rollers 78 and 79, pass upwardly outof the supercooling bath over rollers 86 and 31 and are then suitablydelivered to the package forming apparatus 34 previously described.Package formation occurs in the manner previously de scribed.-

While the utilization of two different types of poly vinylidene chloridefilm has been described in detail in connection with providing avery'flexible film and an oxygen barrier film it will be understood thatthe principles of the present invention are also useful where two pliesof the same type of 'polyvinylidene chloride film are used. By way ofexample, it may be desirable to utilize two plies of oxygen barrier filmin the packaging of a particular food product which is highlysusceptible to spoilage, and in order to maintain adequate flexibilityand strength in the formed package, the use of separating material isparticularly important to prevent fusing of the two plies ofpolyvinylidene chloride film. Fusing of similar or dissimliarpolyvinylidene chloride films may result in a material change in theflexibility, impact strength, tensile strength, etc. of the resultinglaminate and it has been found generally preferable to maintainseparation of the individual plies and thus maintain properties in thelaminate which permits the package to be readily handled without damageunder widely variable temperature conditions.

An example of suitable oxygen barrier polyvinylidene chloride film isthat which has a composition of approximately 90% vinylidene chlorideand 10% vinyl chloride. A composition of approximately 68% vinylidenechloride and 32% vinyl chloride provides a film exhibiting a high degreeof flexibility. The thickness of the oxygen barrier film may preferablybe about 1 mil and the thickness of the highly flexible filmmay be about3 mils. Polyethylene, polyvinyl chloride and polyvinyl alcohol filmshaving thicknesses of about 0.4 to 0.6 mil have been tested as suitableseparating material and the packages formed therefrom have beensubjected to rather severe impact tests. These tests have been carriedout at temperatures of about 32 F. and very few package failuresresulted.

As previously set forth, any suitable oily substance may be used as aseparating material. Silicone oil having a viscosity of centipoises andcommercial grade mineral oil have been tested in the same manner asdescribed above in connection with the use of a separating filmmaterial. Any suitable oil emulsion which is capable of providing anadequate separating film may be used. Plasticizers such as 2-ethylhexyldiphenyl phosphate, dibutyl sebacate and acetyl tributyl citrate may beused and have been tested with favorable results. Suitable mixtures ofplasticizers and mineral oil may also be used.

The foregoing specific examples of usable separating materials aremerely illustrative of many different types of separating materialscapable of use in forming the package of the present invention. .It willbe understood that any separating material capable of preventing fusedcoherence between the combined plies of polyvinylidene chloride filmwhile not interfering with the requisite flexibility and stretchabilitythereof may be used. Similarly, any adequately form-able separating filmmaterial capable of preventing fused coherence between the combinedpolyvinylidene chloride films may be used.

Obviously certain modifications and variations of the invention ashereinbefore set forth may be made without departing from the spirit andscope thereof, and therefore only such limitations should be imposed asare indicated in the appended claims.

We claim:

l. A package for use in merchandising food products and the like, saidpackage comprising a product receiving area covered and enclosed bycooperating laminates of flexible polyvinylidene chloride films, saidfilms exhibiting substantially random crystallization throughout, theenclosing of said product receiving area being obtained by intersealingof peripheral contacting portions of said laminates between thepolyvinylidene chloride films thereof while said polyvinylidene chloridefilms are in their supercooled amorphous and substantially unstretchedstate, at least one of said laminates throughout its portion coveringthe product receiving area comprising inner and outer films ofpolyvinylidene chloride having received therebetween a separatingmaterial which maintains separation of said inner and outer filmswithout reducing the flexibility thereof.

2. The package of claim 1 wherein said separating material is a thinlayer of oil-containing material.

3. The package of claim 1 wherein said separating material is a formablefilm which is non-bendable with supercooled polyvinylidene chloridefilm.

4. The package of claim 1 wherein said separating material is an oil.

5. The package of claim 1 wherein said separating material is aplasticizer.

6. The package of claim 1 wherein said separating material is apolyvinyl chloride film.

7. The package of claim 1 wherein said separating material is apolyethylene film.

8. The package of claim 1 wherein said separating material is apolyvinyl alcohol film.

9. A package enclosing a plurality of products arranged in contactingside-by-side relation, said package being formed from a pair oflaminates each formed from inner highly flexible and outer oxygenbarrier films of polyvinylidene chloride having received therebetween anon-bonded formable separating material, said laminates havingcontacting portions thereof defining a seal along the sides of saidpackage as a result of mutual intersealing of opposed portions of saidpolyvinylidene chloride films while in their supercooled amorphous andsubstantially unstretched state, the remainder of said laminates beingin intimate contact with adjacent surfaces of said products withportions thereof depressed between said products to conform to theshapes thereof along both the top and bottom surfaces of said package,said polyvinylidene chloride films including the seal defining portionsthereof being crystallized throughout with substantially random crystaldistribution.

10. In the method of forming product containing packages from laminatesof supercooled polyvinylidene chloride film wherein separate highlyflexible and oxygen barrier films are continuously formed, immediatelysupercooled, laminated prior to package forming to provide laminates ofhighly flexible and oxygen barrier films, the laminates are combined toenclose and seal a product while being maintained in their supercooledstate, the polyvinylidene chloride films are subsequently crystallizedwithout substantial attendant stretching to establish randomcrystallization throughout, and the packages are thereafter separated,the improvement which comprises introducing between the polyvinylidenechloride films of each laminate a formable separating material prior topackage forming while said films are in their supercooled state toprevent overall polyvinylidene chloride film fusing in each laminate.

11. The method of claim 10 wherein the separating material is a thinlayer of oil which is supplied from a pocket of oil trapped between thepolyvinylidene chloride films undergoing lamination.

12. The method of claim 10 wherein the separating material is a formablefilm which is non-bondable with supercooled polyvinylidene chloridefilm, the formable film being continuously fed between thepolyvinylidene chloride films undergoing lamination.

References Cited in the file of this patent UNITED STATES PATENTS2,635,742 Swartz et al. Apr. 21, 1953 2,679,968 Richter June 1, 19542,711,779 Carland June 28, 1955 2,715,458 Polglase Aug. 16, 19552,718,303 Polglase Sept. 20, 1955 2,730,161 Langer Jan. 10, 19562,815,896 Shapero et al. Dec. 10, 1957 2,956,855 Havens Oct. 18, 1960FOREIGN PATENTS 534,535 Great Britain 2 Mar. 10, 1941 788,536 GreatBritain Jan. 2, 1958 142,069 Australia July 9, 1951

1. A PACKAGE FOR USE IN MERCHANDISING FOOD PRODUCTS AND THE LIKE, SAIDPACKAGE COMPRISING A PRODUCT RECEIVING AREA COVERED AND ENCLOSED BYCOOPERATING LAMINATES OF FLEXIBLE POLYVINYLIDENE CHLORIDE FILMS, SAIDFILMS EXHIBITING SUBSTANTIALLY RANDOM CRYSTALLIZATION THROUGHOUT, THEENCLOSING OF SAID PRODUCT RECEIVING AREA BEING OBTAINED BY INTERSEALINGOF PERIPHERAL CONTACTING PORTIONS OF SAID LAMINATES BETWEEN THEPOLYVINYLIDENE CHLORIDE FILMS THEREOF WHILE SAID POLYVINYLIDENE CHLORIDEFILMS ARE IN THEIR SUPERCOOLED AMORPHOUS AND SUBSTANTIALLY UNSTRETCHEDSTATE, AT LEAST ONE OF SAID LAMINATES THROUGHOUT ITS PORTION COVERINGTHE PRODUCT RECEIVING AREA COMPRISING INNER AND OUTER FILMS OFPOLYVINYLIDENE CHLORIDE HAVING RECEIVED THEREBETWEEN A SEPARATINGMATERIAL WHICH MAINTAINS SEPARATION OF SAID INNER AND OUTER FILMSWITHOUT REDUCING THE FLEXIBILITY THEREOF.